Effect of a novel injectable hydrogel implant on ventricular remodeling in rabbits with experimental myocardial infarction / 中华心血管病杂志

<p><b>OBJECTIVE</b>To observe whether injectable hydrogel implantation could prevent adverse cardiac remodeling and preserve cardiac function in rabbits with myocardial infarction (MI).</p><p><b>METHODS</b>A novel injectable hydrogel, the copolymer MPM/alpha-CD, which self-assembled between alpha-cyclodextrin and methoxy polyethylene glycol-poly (caprolactone)-(dodecanedioic acid)-poly (caprolactone)-methoxypolyethylene glycol triblock polymer, was synthesized by chemical crosslinking and characterized by biocompatibility and biodegradability. Experimental MI was induced in male rabbits by coronary artery ligation. The MI rabbits were randomly divided into hydrogel group (200 microl MPM/alpha-CD were injected into the infarcted myocardium 7 days after MI) and control group (equal volume phosphate buffered saline myocardial injection, n = 8 each). Four weeks after MPM/alpha-CD implantation, echocardiography, histochemistry and immunohistochemistry were performed.</p><p><b>RESULTS</b>Left ventricle ejection fraction was significantly improved in the hydrogel-treated group (56.1% +/- 8.4%) than that in the control group (37.3% +/- 6.4%, P < 0.05). Histological analysis indicated that hydrogel degraded 4 weeks after hydrogel injection, and prevented scar expansion and wall thinning [(3.08 +/- 0.32) mm vs. (2.18 +/- 0.46) mm in control group, P < 0.05]. Neovasculature formation was similar between the hydrogel group [(100.8 +/- 2.4)/mm(2)] and the control [(98.5 +/- 2.9)/mm(2), P > 0.05].</p><p><b>CONCLUSION</b>MPM/alpha-CD could serve as an excellent injectable biomaterial for improves cardiac function and attenuating scar expansion and left ventricular dilation in MI rabbits.</p>

Experimental study of replacement of an esophageal segment with an nitinol alloy composite artificial esophagus / 中华外科杂志

<p><b>OBJECTIVE</b>To observe the feasibility of a segment thoracic esophagus replaced by using a nitinol alloy composite artificial esophagus.</p><p><b>METHODS</b>A nitinol alloy composite artificial esophagus was made of a nitinol tube coated with a silicone membrane with a dacron flange 1 cm proximal to each end. There were ten pigs for the models of experimental animal. The models of experimental animal were established by excised a segment of 7 cm long thoracic esophagus and replaced with the graft. In accordance with the different anastomosis connective way 10 pigs were divided into group I and group II, every group had 5 pigs. In group I monolayer end-to-end anastomosis was used with this prosthesis. In group II monolayer end-to-end anastomosis was used with this prosthesis and above the site of anastomosis adding dacron strip fixed. After operation the operate animals were observed for eating and health. Esophagography and flexible esophagoscopy were performed once a month at the first, second, and third postoperatively month. Three pigs of the grafted prostheses sloughed out spontaneously at different postoperatively period were killed for autopsy and pathologic examination of the neoesophagus.</p><p><b>RESULTS</b>All pigs had no leakage at the site of anastomosis and survived over 6 months. The longest survival was 20 months. Seven of 10 pigs the grafted prostheses sloughed out spontaneously at 2 to 6 months after the operation (4 in group I and 3 in group II). The grafted prostheses sloughed out spontaneously less than 3 months after operation, marked neoesophageal stenosis in the grafted portion was recognized (3 in group I). They displayed serious difficulty in eating. But the prostheses sloughed out spontaneously more than 3 months after operation, neoesophageal stenosis was increased slightly and the stenosis was only temporary and gradually resolved. (1 in group I, 3 in group II) They lived in good health and without difficulty in eating. Three of 10 pigs the grafted prosthesis still stayed in the grafted place over 10 months (1 in group I, 2 in group II). The neoesophageal had no stenosis. They were perfectly well in eating.</p><p><b>CONCLUSIONS</b>A segment excised pig esophagus replaced with a nitinol alloy composite artificial esophagus is feasible and takes a better result.</p>